30 cigarettes a day is equivalent to 160 mSv per year, or over three times the legal limit for a U.S. worker involved in work that exposes him to radiation (which is about 50 millisieverts). As a reference, background radiation in much of the world is around 2-3 mSv/year.

160 mSv is a radiation dosage roughly equal to 2000 chest X-rays per year, or 5.5 chest X-rays per day. Which also means that every 5.45 cigarettes one smokes, they’re getting a chest X-ray.

According to this article, the radiation is due to the presence of radioactive lead-210 and polonium-210 in the fertilizer and soil used to grow tobacco leaves.

Since finding out about this, every time I see a smoker, I think to myself about the radiation they’re breathing in, and how oblivious they are to it. The worst part is it’s pointless telling them, since the reaction is usually complete disbelief!

Smokers aren’t just breathing in substances that are wildly carcinogenic, they’re breathing in radiated dust too. I don’t know about you, but I hold my breath when I walk past a cloud of smoke.